Carbon dioxide (CO2) capture embodies ongoing research. The ultimate goal in CO2 sequestration is to first capture it, then redirect it to a long term storage paradigm.
Solid sorbents have been envisioned for capture of CO2 and other targeted moieties. Such sorbents include zeolites, porous carbon, organic molecular crystals, and metal organic frameworks (MOFs). But these state of the art adsorbents exhibit poor chemical and thermal stability, particularly under practical CO2 capture processes which embody low CO2 concentrations (e.g., below about 20 percent). Examples of the shortcomings of the prior art include the following:
Low CO2 uptake or/and high CO2 uptake with additional energy requirement at the desorption step.
Low CO2 separation performance over other gasses present in the gas stream
High energy output to release captured CO2 
Complex material design and preparation.
Efforts to create polymeric adsorbents continue to fall short. One of the drawbacks experienced is the generation of soluble oligomers due to inefficient cross linking between reactants (e.g., benzene and tetrahydrochloride). Also, many methods require metal catalysts which require their removal during product purification.
Furthermore, pore size distribution of the best state of the art adsorbents are no less than 0.68. (Pore size distribution is average spherical pore size. It is determined by fitting N2 adsorption isotherms (collected at 77 K) of materials. Non local density functional theory calculates the pore size distribution based on the isotherm.) This state of the art pore size distribution value is too large (pores are too wide) to enable the surface energies necessary to adsorb target moieties at typical (i.e. low) flue concentrations.
Efforts have been made to combine microporous polymers with inorganic particles. These mixed matrix membranes were created to improve gas transport properties. However, many of these composites experience delamination such that voids form at the polymer-particle interface. This reduces gas selectivity.
A need exists in the art for a sorbent having much enhanced affinity for carbon dioxide at typical flue effluent concentrations. Strong interaction between CO2 and the framework of the sorbent is needed due to the low partial pressure of CO2 in flue gases. The sorbent should have a pore diameter of no greater than about 3 nm and preferably no greater than about 2 nm. The sorbent should exhibit narrow pore size distribution and a high percentage of functional sites for CO2 capture and separation. A need also exists for a simple and inexpensive method to making the sorbent. For example, the method should employ a minimal number of steps and utilize relatively common reactants and be template free.